Thermal and laser angioplasty results in altered endothelial surfaces which may predispose to platelet adhesion and enhanced thrombogenicity. Therefore, to compare acute surface thrombogenicity for different energy sources, atherosclerotic hereditable hyperlipidimic rabbits were exposed to either an ultraviolet pulsed excimer laser, and infrared pulsed erbium-YAG laser, or a catalytic hot tipped catheter to produced comparable longitudinal surface troughs. The segments were perfused with human blood in an anular flow chamber and microscopic morphometry was performed to determine the percent surface area of treated and control sites covered with either adherent platelets or platelets thrombi. Interestingly, thermal ablation using either an erbium-YAG laser or a hot tipped catheter resulted in diminished surface thrombogenicity compared to control sites of excimer laser tissue ablation. These data suggest that precise microablation using ultraviolet pulsed laser sources result in a less favorable thrombogenic surface than thermal tissue ablation.